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Man Overboard in Cold Water

Published on May 6th, 2014

by Capt. Jack McClurkin
With the ice cover on Lake Michigan this winter, sailors this year will experience cold water sailing well into summer. It is likely that surface water temperatures will be in the 40’s and 50’s in May and June. Although the air might be warm, the cold water is dangerous to the human body. For a study of the effect of cold water, a professor had some subjects jump into 45 degree water and attempt to swim just 30 feet.

None made it. Fortunately, they were accompanied by a trained Coast Guard swimmer in a dry suit. All subjects survived.

Here is what happens when the body is immersed in cold water. Within two minutes of immersion, an involuntary gasp reflex occurs. If the head is not above water when the gasp reflex occurs, there is the possibility that the person will not resurface. You may have read reports where a person went into the water and never resurfaced. Now you know one reason why this can occur.

From 2 to 10 minutes after cold water immersion, the involuntary part of the brain begins to realize that it is a bit too chilly. The body’s core temperature begins to drop. Then the brain acts to protect the organs by diverting blood away from the muscles. As a result, the muscles quit working. The arms and legs stop moving and won’t keep the person in the water afloat. You may have read reports of someone in the water who suddenly went underwater and never resurfaced. Now you know why. It doesn’t matter that you consider yourself to be an Olympic-class swimmer, the muscles stop working.

From 30 minutes to four hours after immersion, hypothermia sets in.

The first 10 minutes after immersion are critical for a person in cold water without floatation. If you are sailing under spinnaker on a screaming reach, it may well take all of those precious 10 minutes to return to the place where the person went overboard.

Here are some simple safety steps that sailors can take during cold water sailing to improve the survival chances of a person immersed in cold water:

1. Insist that all crew wear lifejackets at all times. No exceptions. Don lifejackets on the dock before boarding, and keep them on during the entire voyage. If a lifejacket is uncomfortable to wear, buy one that is comfortable. A stowed lifejacket is nearly useless. But when worn it can be very useful to keep the head out of the water during the gasp reflex, and to stay afloat when the muscles stop working, significantly improving survivability.

2. Before you leave the dock for the first time, make sure that all safety gear is onboard. This includes the delivery trip from the yard to the summer dock. A ring buoy, man overboard pole, radio, or Life Sling won’t do much good if you need it and it is still in storage.

3. On the first sail of the season practice a man overboard drill – not just a fender fetch. Practice as if the person in the water won’t be able to climb a swim ladder, and may not be able to attach the sling. Your drill needs to retrieve the fender with the Life Sling or harness and raise it onboard with a hoist or halyard. Repeat the drill when new crew members are aboard or at least monthly. If you arrive at the starting area of a race early, do a practice drill.

4. Know how to use the radio to call emergency services. In some areas 911 operators want to enter a street address to direct land-based emergency crews. This could be a problem if you are on the water and there isn’t an address in their database for the closest dock. Know the procedure in your area. A loss of core body temperature of only a few degrees is serious. Have the person who was immersed checked out by medical personnel.

5. Have all crew wear lifejackets at all times. Oh, am I repeating myself?

NOTE: For further reading, search the internet for “cold water immersion.” Read about the signs of hypothermia and the onboard care for a person recovered from cold water. Even though the water will be cold, sail safely this summer! The author holds a USCG Master’s license and has been sailing for 50 years. During the summer he drives a commercial passenger riverboat in Chicago, sails his Flying Scot, and crews on a Tartan Ten

Source: Lake Michigan Sail Racing Federation,

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